Cold end glassware coating apparatus

ABSTRACT

An apparatus for forming a coating on glassware articles comprises a source of pressurized air and source of liquid coating material. The source of liquid coating material includes a reservoir and a vapor-forming chamber. An adjustable gas pressure regulator provides a regulated gas pressure in the reservoir and a regulated flow of liquid coating material out of the reservoir. A plurality of vapor-forming atomizers are positioned and configured to atomize the liquid coating material and direct the coating material vapor into the vapor chamber. The apparatus further includes a vapor booth and a conveyor operable to convey glassware articles to the vapor booth to be coated. A plurality of fans provide circulating flows of coating material vapor within the booth and along the conveyer portion.

FIELD OF THE INVENTION

This invention relates to an effective new apparatus for forming aneffective single, inexpensive, thin, transparent cold end coating forglassware that remains tenacious, lubricous and protective afterexposure to high temperatures and sterilization and does not interferewith labeling of the glassware.

BACKGROUND OF THE INVENTION

Formation of durable lubricous coatings have been found to be of greatimportance in the glass container industry to provide glass articles, orware, with at least one layer of an adhering lubricating material inorder to facilitate high speed automatic handling of glass articles inproduction lines, to protect articles against contact abrasion damage,and to prevent unsightly scuff and scratch damage. In this regard,uncoated glass articles are highly susceptible to abrasion damage, andit has been reported that newly formed uncoated glass articles canquickly lose up to 75% of their bursting strength due, at least in part,to surface abrasion caused by contact with other glass articles asnormally occurs during processing and handling of such articles.

While some coatings have been applied to articles just prior to use, tobe fully effective, the articles should be coated soon after they areformed, and in the case of annealed articles, for example, such coatingshave been applied immediately before and/or after annealing.

In practice, pre-annealing coatings, sometimes referred to as "hot end"coatings, are applied to glassware after it leaves the glassware machinein an initial coater. The initial coater forms a very thin metal oxidecoating on the outer surface of the glassware, which is then carried tothe annealing lehr. Such pre-annealing coating methods and apparatus aredisclosed, for example, in U.S. Pat. Nos. 4,431,692; 4,615,916;4,668,268; 4,719,126; and 4,719,127 and others listed below.

A number of post-annealing coatings, sometimes referred to as "cold end"coatings, and methods and apparatus for their application, have beendisclosed, for example, in U.S. Pat. Nos. 2,995,533; 3,386,855;3,487,035; 3,712,829; 3,801,361; 3,876,410; 3,989,004; 3,997,693;4,039,310; 4,130,407; 4,135,014; 4,517,242; 4,517,243; 4,529,657 and4,812,332.

U.S. Pat. Nos. 3,876,410 and 3,989,004 disclose an apparatus and methodfor applying a coating material that is, at least in part, vaporizableat a readily obtainable temperature and capable of producing vapor thatis contact-adherent to the article to be coated to produce a durable andtenacious, lubricous coating. In general, the patents disclose methodand apparatus for forming acceptable coating material from organicmaterials, particularly hydrocarbons formed from methylene, ethylene,propylene, butylene, fatty acids and their derivatives and the like.

Caproic acid, stearic acid, oleic acid, myristic acid, linoleic acid andpalmatoleic acid are disclosed as typical of the compositions yieldingdesirable coatings on glassware when used in the method and apparatus ofthese patents.

Oleic acid has been used in the commercial practice of the inventions ofthese patents. Oleic acid is a bland liquid in normal condition, havingan appearance similar to that of cooking oil. It has been approved foruse in connection with food products. As little as 1 drop of oleic acidevery 17 seconds has been found sufficient to produce an acceptablelubricating coating on catsup bottles passing through the vapor at therate of 80 bottles per minute. Thus, 1 drop of oleic acid providessufficient vapor to coat about 20 catsup bottles. Further, oleic acid isreadily available in high-grade quality at low cost. Because of theseadvantages, oleic acid has been a primary coating material used toprovide post-annealing coatings.

The apparatus used to apply oleic acid in commercial practice includes ahood forming a vapor booth for a portion of a conveyer, which isoperated to carry articles of glassware through the vapor booth. Thevapor booth includes, generally, a booth top and an upper plate and aplurality of partitions between the booth top and the upper plateforming a plurality of plenum chambers arranged, one after the other,over and along the conveyer portion. The sides of the vapor booth areformed by a pair of downwardly extending panels that provide not onlythe means to support the vapor booth with respect to the conveyer, but aplurality of flow directing and controlling vanes in communication witheach of the plurality of plenums. The upper plate of the vapor booththat forms the top of the plurality of plenums has a plurality ofopenings, one in each of the plurality of plenums, for carrying a fan ineach of the plurality of plenums. The booth top also has a plurality ofopenings, at least one for each plenum, permitting vapor flow betweenthe plurality of plenums and the booth formed by the booth top andsides. The upper plate carries a plurality of flow producing fans andfan motors, with one fan being located in each plenum, and the fans arecapable of being rotated by their fan motors in alternatively oppositedirections to provide counter-rotating flows of coating material vaporwithin the vapor booth and along the conveyer portion.

A plurality of vapor flows of oleic acid coating material are introducedthrough a plurality of vapor discharge tubes located to direct the flowof coating material vapor into the circulating flow of each plenum. Thevapor of oleic acid coating material is formed by means forming a liquidcoating reservoir including a bottom, four sides and a top. The oleicacid, which has a melting point of 57° F. (14° C.), is in a liquidstate. The reservoir top also carries a vapor-forming nozzle having itsliquid outlet connected with the coating material in the reservoir by aninlet tube extending from the vapor-forming nozzle to adjacent thereservoir bottom. The vapor-forming nozzle is also connected with asource of pressurized air for vaporization of the oleic acid coatingmaterial, and the vaporized coating material and pressurized air aredirected from the vapor-forming nozzle through the reservoir top andinto the reservoir, where the non-vaporous particles were removed bygravity. The remaining oleic acid vapor is urged by the influence of thepressurized air to and through the vapor discharge tube and introducedinto the vapor hood for application to the glassware.

In practice, the oleic acid glassware coating is frequently supplementedby an additional cold-end coating using polyethylene to permitsterilization of the glassware. Oleic acid is liquid at temperatures inexcess of 57° F. (14° C.). When glassware coated with oleic acid aloneis exposed to elevated temperatures, such as in an autoclave for thesterilization of food containers, such as baby food jars, the oleic acidcoating is substantially removed by the harsh and hot conditions, andthe scratch resistance and lubricity are deleteriously affected, therebyincreasing the risk of breakage. Breakage during processing is seriousbecause of the possibility of slivers or fragments of the shatteredglass being deposited in adjacent ware, which is completely unacceptablewhen the ware is to be used for food packaging.

DISCLOSURE OF THE INVENTION

This invention provides an effective, new, economically operableapparatus for providing glassware with a single, improved, non-toxic,tenacious, lubricous and protective cold end coating that retains itslubricity and protective qualities after exposure to the hightemperatures and harsh conditions of sterilization, remains transparentand does not interfere with labeling. This invention permits reducedcoating costs, the elimination of supplemental cold end coatings, suchas polyethylene, and increased lubricity and durability of the cold endcoating.

The apparatus of the invention permits the application of a cold endcoating with coating materials having high temperature melting points,for example, coating materials having melting points in excess of 200°F.-250° F. Apparatus of the invention includes means for providing aregulated flow of heated and liquified coating material; vapor-formingmeans for forming the flow of heated and liquified coating material intoa coating material vapor with a heated and regulated flow of gas, and athermally isolated and partially heated vapor booth connected with thevapor output of the coating material vapor-forming means and enclosing aportion of a conveyer which carries the glassware through the vaporbooth. In the invention, the means for providing a regulated flow ofheated and liquified coating material comprises a source of liquidcoating material, including a reservoir having a top, a bottom and asidewall therebetween, an electric heater for the reservoir, an inletfor a pressurizing gas formed in said reservoir and connected with anadjustable gas pressure regulator, a coating material outlet tubecarried by the reservoir with withdrawal opening adjacent the reservoirbottom, a level sensor carried by the reservoir to signal the level ofliquid coating material in the reservoir, and temperature sensorproviding a signal for control of the electric heater to maintain theliquid state of coating material in said reservoir. The vapor-formingmeans of the invention comprises a vapor chamber including a top, abottom and a sidewall therebetween, a second electric heater for thevapor chamber, a plurality of vapor-forming atomizers carried by thechamber top, each of the plurality of vapor-forming atomizers having acoating material inlet connected with the outlet tube of the coatingmaterial reservoir for receipt therefrom of the regulated flow of heatedand liquified coating material, and also having an atomizing air input.Each of the vapor-forming atomizers have coating material and atomizingair outlets coacting to form and direct coating material vapor into thevapor chamber, and each of said atomizing air inlets of said pluralityof vapor-forming atomizers are connected with an air heater that isconnected through an air flow regulator with a source of compressed air.

In the invention, the vapor-forming atomizers atomize the coatingmaterial and direct the atomized coating material vapor and heatedatomizing air into the vapor chamber. The resulting coating materialvapor is urged from the vapor chamber by the further flow of heatedatomizing air into the thermally isolated and partially heated vaporbooth, which includes at least one plenum means having an opening incommunication with the enclosed conveyer portion and fan means forcreating a circulation of the coating material vapor within the plenumand the enclosed conveyer portion.

The thermally isolated and partially heated vapor booth preferablycomprises a booth top and upper plate and a plurality of partitionsforming a plurality of plenum chambers arranged, one after the other,over and along the enclosed container portion, and a pair of downwardlyextending side forming means for the vapor booth. The booth side formingmeans are open, and in communication with each of a plurality ofplenums, and carry a plurality of flow directing and controlling vanes,and can be used to support the vapor booth with respect to the conveyerportion. The upper plate of the vapor booth has a plurality of openings,one in each of the plurality of plenums, for carrying a fan in each ofthe plurality of plenums. The booth top has a plurality of openings, atleast one for each plenum, permitting vapor flow between the pluralityof plenums and the conveyer enclosure formed by the booth top and sides.Preferably, the booth top carries at least one controllable heater ineach plenum, providing heat to the plurality of plenums and to theenclosed portion of the conveyer. A plurality of flow producing fans andfan motors are carried by the upper plate with one fan being located ineach plenum. The plurality of fans are preferably rotated by their fanmotors in alternating opposite directions to provide a plurality ofcounter-rotating flows of coating material vapor within the conveyerenclosure along the conveyer enclosed conveyer portion, and a pluralityof vapor discharge tubes, each being in communication with the vaporoutput of the coating material reservoir, extend into the booth and arearranged at a plurality of locations along the enclosed conveyerportion, with at least one vapor discharge tube being located to directa flow of coating material vapor into the flow of each plenum. Further,the vapor booth may be provided with a thermally insulating enclosure.

When necessary, the apparatus can include a vapor confining plate belowthe enclosed conveyer portion and under the vapor booth.

Further features and advantages of the invention are shown and describedin the drawings and the further description of the invention thatfollows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the apparatus of the invention;

FIG. 2 is a front view of the apparatus of FIG. 1 showing the interiorof one of the control enclosures and the enclosed means for providingand for atomizing a heated and liquified flow of coating material toprovide coating material vapor;

FIG. 3 is a partial top view of the apparatus of FIG. 1;

FIG. 4 is a cross-sectional view of FIG. 3 taken at a planecorresponding to line 4--4 of FIG. 3 and showing circulation within theapparatus and with respect to a plurality of glassware articles shown inphantom line;

FIG. 5 is a cross-sectional view of the vapor-forming atomizers takenalong line 5--5 of FIG. 2;

FIG. 6 is a cross-sectional view of FIG. 8 taken at a planecorresponding to line 6--6 of FIG. 8.

FIG. 7 is a cross-sectional view of the apparatus of FIGS. 1, 3 and 4taken at a plane corresponding to line 7--7 of FIG. 4;

FIG. 8 is a cross-sectional view of the apparatus of FIGS. 1, 3 and 4taken at a plane corresponding to line 8--8 of FIG. 7 and showing theinterior of the booth side forming means; and

FIG. 9 is a view of an alternative embodiment of the apparatus shown inFIG. 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

FIGS. 1-8 show of an apparatus 10 of the invention. FIG. 1 is a sideview of the apparatus 10 showing means 11 for connecting the apparatuswith a source of pressurized air, an enclosure 20 (shown in phantomlines in FIG. 1) for means 21 (FIG. 2) for providing a flow of heatedand liquified coating material and vapor-forming means 31 (FIG. 2) forthe flow of heated and liquified coating material, and a thermallyisolated and partially heated vapor booth 40.

As shown in FIGS. 1 and 4, and described in greater detail below, themeans 40 forming the vapor booth encloses a portion of a conveyer 12 forcarrying glassware (indicated in phantom line in FIG. 4) through thevapor booth. FIG. 4 is a cross-sectional view of the means 40 formingthe vapor booth taken at a plane corresponding to line 4--4 of FIG. 3,which is a partial top view of the apparatus of the invention. As shownin FIGS. 1 and 4, the apparatus may be provided with a vapor confiningplate 13 below the enclosed conveyer portion and under the vapor booth40.

The means for providing and vaporizing a flow of heated and liquifiedcoating material are shown in greater detail in FIGS. 2 and 5.

As shown in FIG. 2, the enclosure 20 houses a means 21 for providing aregulated flow of heated and liquified coating material and avapor-forming means 31 for forming the regulated flow of heated andliquified coating material from the coating material source 21 into acoating material vapor with a heated and regulated flow of gas. Themeans 21 forming a source of liquid coating material includes areservoir 22 having a top 22a, a bottom 22b and a sidewall 22ctherebetween. An electric heater 23 for the reservoir 22 is connected ingood thermal contact with the sidewall 22c of the reservoir 22. Thereservoir 22 also includes an inlet 24 formed therein for receipt of apressurizing gas. As shown in FIG. 2, the interior of closure 20 carriesan adjustable gas pressure regulator 60 having its outlet 61 connectedwith reservoir inlet 24 and its inlet 62 arranged for connection withmeans 11 for providing pressurized air to the apparatus. The reservoir22 also carries an outlet tube 25 having a withdrawal opening 25aadjacent the bottom 22b of the reservoir 22. The reservoir 22 alsocarries means 26 for providing a signal of the level of liquid materialin the reservoir 22 and a temperature sensor 27 for providing a controlsignal for the electric heater 23 to maintain the liquid state ofcoating material in reservoir 22. The temperature sensor 27, theapparatus control and electric heater 23 can cooperate in a way known inthe art, to maintain the interior of reservoir 22 at temperatures up to200° F.-250° F. The adjustable gas pressure regulator 60 provides aregulated gas pressure of, for example, 0-20 psi, within the reservoir22 and an adjustable regulated flow of heated and liquified coatingmaterial from the outlet tube 25.

As further shown in FIG. 2, the means 31 for forming a coating materialvapor is connected with outlet tube 25. The vapor-forming means 31includes a vapor chamber 32 having a top 32a, a bottom 32b and asidewall 32c therebetween. A second electric heater 33 for the vaporchamber 32 is thermally connected with the sidewall 32c of the vaporchamber 32 and is operated by the apparatus control in response to asecond temperature sensor (not shown) to maintain the vapor chamber oftemperatures at 200° F.-250° F. A plurality of vapor-forming atomizers34 is carried by the top 32a of the vapor chamber 32.

FIG. 5 is a partial cross-sectional view taken at a plane correspondingto the line 5--5 of FIG. 2 to illustrate the vapor-forming atomizers 34in greater detail. In FIGS. 2 and 5, each of the plurality ofvapor-forming atomizers 34 have a coating material inlet 34a that isconnected with the outlet tube 25 of the coating material source 22 andreceives therefrom a regulated flow of heated, liquified coatingmaterial. Each of the plurality of atomizers 34 also has an atomizingair inlet 34b, and each of the atomizing inlets 34b of the plurality ofvapor-forming atomizers 34 is connected with an air heater 35 whichprovides, as further explained below, a regulated flow of heatedatomizing air. As shown in greater detail in the cross-section of FIG.5, each of the vapor-forming atomizers 34 direct their respectiveinterior flows of atomizing air and heated, liquified coating materialto coact in forming a coating material vapor and direct coating materialvapor from their vapor outlets 34c into the vapor chamber 32.

As further shown in FIG. 2, the enclosure 20 houses, in addition to thesource of coating material 21 and the coating material vapor-formingmeans 31, an air heater 35 and an air flow regulator 63, which isconnected to the input of air heater 35. Air heater 35 may also beself-controlled to maintain the temperature of the air at its outlet inthe range of 200° F.-250° F. The air flow regulator 63 includes a flowmeter 64 to provide a visual indication of the flow rate of atomizingair through the air heater 35 and the plurality of vapor-formingatomizers 34, and an adjustable air flow regulator 65 is used to adjustthe flow of air to the vapor-forming means 31 to provide coatingmaterial vapor from the regulated flow of heated and liquified coatingmaterial from the outlet 25 of coating material source 21.

According to a preferred embodiment of the invention, as shown in FIG.9, means 121 for providing a regulated flow of heated and liquifiedcoating material includes a single tank 110 having a vapor chamber 115and a reservoir 122 separated by a partitioning wall 117. A one-waycheck valve 119 provides communication through the partitioning wall 117between the reservoir 122 and the vapor chamber 115.

The reservoir 122 includes a top 122a, a bottom 122b and a sidewall 122ctherebetween. An electric heater 123 for the reservoir 122 is connectedin good thermal contact with the sidewall 122c of the reservoir 122. Thereservoir 122 also includes an inlet 124 formed therein for receipt of apressurizing gas. An outlet tube 125, positioned in the reservoir 122has a withdrawal opening 125a adjacent the bottom 122b of the reservoir122.

The reservoir 122 further includes an internal temperature sensor 127for providing a control signal for electric blanket heaters 123. Thetemperature sensor 127, the apparatus control and the electric blanketheater 123 can cooperate in a way known in the art, to maintain theinterior of the reservoir 122 at temperatures up to 200° F.-250° F. Anadjustable gas pressure regulator 60 provides a regulated gas pressureof, for example, 1-20 psi within the reservoir 122 and an adjustableregulated flow of heated and liquified coating material from the outlettube 125.

Vapor-forming means 131 is positioned on top of the vapor chamber 115and includes a plurality of vapor-forming atomizers 134. A commerciallyavailable cartridge heater (not shown) is coupled to the vapor-formingmeans 131 to heat the vapor-forming means 131 and, thereby the incomingair to prevent a deleterious solidification of the coating material.Vapor formed by the atomizers 134 is carried into the vapor chamber 115and through vapor outlets 148 to the vapor booth 40. The lower portionof the vapor chamber 115 includes a recovery chamber 129 for collectingthe portion of the vapor that doesn't go through the outlets 148 to thevapor booth 40. The portion of the vapor that eventually falls to thebottom of the vapor chamber 115 is collected and returned to thereservoir 122 by periodically pressurizing the vapor chamber 115 andforcing the collected vapors through the check valve 119 into thereservoir 122.

The preferred embodiment has a major thermal advantage. That is, the useof a single tank to house the vapor chamber 115 and the reservoir 122minimizes the use of external fluid lines, thereby reducing thelikelihood of unwanted solidification of the coating material.Specifically, outlet tube 125 passes heated and liquified materialbetween the reservoir 122 and the vapor-forming means 131 directlywithout leaving the heated tank 110. As a result, the cartridge heater(not shown) in the vapor-forming means provides sufficient heat toenable operation of the apparatus without resorting to external heatingof the air flow. Thus, the air heater (35 in FIG. 2) is eliminated fromthe presently preferred embodiment, thereby reducing complexity of theequipment and reducing the manufacturing and operating costs of theinvention.

"Vapor" as used in this application refers to atomized coating materialparticles small enough (that is, having a sufficiently small mass tosurface ratio) that they are carried by a quiescent flow of air, forexample, particles with the diameter of a few microns.

The vapor formed by the plurality of vapor-forming atomizers 34 of theFIG. 2 embodiment is carried from the vapor chamber 32 through outlets48 (FIG. 3) to the means forming a vapor booth 40. As shown in FIGS. 2and 5, as a result of operation of the apparatus, a flow of heated airis directed from the adjustable air flow source 63 and air heater 35through the plurality of vapor-forming atomizers 34 and from theiroutlets 34c into the vapor chamber 32. The pressurization resulting inthe vapor chamber 32 creates an outward flow of heated air and vaporwhich may be directed into the means 40 forming a vapor booth as shownin FIG. 3.

When the level in coating material in reservoir 22 becomes too low,level sensor 26 will provide an output signal and operate a warning atthe apparatus control to advise the personnel responsible for operationof the apparatus that the coating material in reservoir 22 should bereplenished.

In the embodiment of FIG. 9, a flow of air is directed from theadjustable air flow source through inlet 124 and into reservoir 122 topressurize the reservoir 122 and thereby urge liquid coating materialthrough the outlet tube 125 to the vapor-forming atomizers 134. At thesame time, a flow of air is directed from the adjustable air flow sourcethrough the plurality of vapor-forming atomizers 134. As the air flowpasses through the vapor-forming atomizers 134, it atomizes the liquidcoating material and directs the resultant vapor into the vapor chamber122. The inflow of vapor pressurizes the vapor chamber 122, therebycreating an outward flow of air and vapor which may be directed throughthe outlets 148 and into the means forming a vapor booth 40.

As noted above, the system also includes means 40 forming a vapor boothfor a portion of a conveyer 12 which carries articles of glasswarethrough the vapor booth 40. The means 40 forming the vapor booth isshown in greater detail in FIGS. 3 and 4, and 6-8. The means 40 forms athermally isolated, partially heated vapor booth connected with thevapor output of the coating material reservoir 22. Means 40 forms atleast one plenum 41, and preferably a plurality of plenums 41, having atleast one and preferably two openings 41a in communication with theenclosed conveyer portion 12 and also having fan means 42 for creating acirculation of coating material vapor within the plenum 41 and theenclosed conveyer portion 12, as shown in FIG. 4. As shown in FIGS. 3, 4and 7 the preferred plurality of plenums is formed by a booth top 43, anupper plate 44 and a plurality of partitions 45. As best shown in FIG.3, the plurality of partitions 45 form a plurality of plenums 41arranged one after the other, over and along the conveyer portion 12.

Means 40 further includes a pair of downwardly extending side formingmeans 46 forming the vapor booth. The booth side forming means canprovide means 49 for supporting the vapor booth from the structure 12aof conveyer portion 12 as shown in FIG. 4. As shown in FIGS. 4, 6, 7 and8, each of the side forming means 46 is open and in communication witheach of the plurality of plenums 41 at the plenum openings 41a. As bestshown in FIGS. 6-8, each of the side forming means 46 carries aplurality of flow directing and controlling vanes 46a.

As indicated in FIGS. 3 and 4, the upper plate 43 has a plurality ofopenings one at each of the plurality of plenums 41 for carrying fanmeans 42 in each of the plurality of plenums 41. The booth top 44 alsohas a plurality of openings 44a, at least one for each plenum,permitting vapor flow between the plurality of plenums 41 and theconveyer enclosure formed by the booth top and sides of means 40. Thebooth top 44 can carry one or more strip heaters to help maintain theenclosed conveyer portion above the melting point of the coatingmaterial. Preferably, the booth top 44 carries a plurality of stripheaters, with at least one strip heater being carried in each plenum,and each of the plurality of strip heaters is individually controllableto provide a maintained temperature in each plenum. The strip heaterscan be located at any convenient location on the booth top 44 and arenot shown in the figures.

As shown in FIG. 4, the fan means 42 comprise a plurality of flowproducing fans 42a and fan motors 42b carried by the upper plate 43 withtheir respective fans 42a being located in each of the plenums 41. Asindicated in FIG. 3, the fans 42a are preferably rotated by their fanmotors 42b in alternating, opposite directions, as shown in FIG. 3clockwise at the top, counterclockwise in the center, and clockwiseagain at the bottom of FIG. 3. The alternating opposite directionsprovide a plurality of counter-rotating flows of coating material vaporwithin the conveyer enclosure along the conveyer portion 12.

As indicated in FIG. 3, a plurality of vapor discharge tubes 47 areconnected through a conduit 48 with a vapor output of the coatingmaterial reservoir 22. The plurality of discharge tubes 47 extend intothe means 40 forming the vapor booth from each side of the vapor booth(only one side being shown in FIG. 3). The outlets 47a of the pluralityof discharge tubes 47 can be arranged at a plurality of locations alongthe conveyer portion, as shown in FIG. 3, to direct a flow of coatingmaterial vapor into the flow of each plenum. As shown in FIG. 4, thecoating material vapor will be carried by the counter-rotating flowswithin the plenum and enclosed container portion to encompass and coatglassware carried by the conveyer 12. As further indicated in FIGS. 4,6, 7 and 8, the means 40 forming the vapor coating booth may, ifdesired, be provided with a blanket of insulation 50.

The means 40 illustrated in FIGS. 3, 4 and 6-8 is intended for use witha glassware production line having a width, as measured by conveyorwidth, of up to about eight feet. Where the production line is widerthan about eight feet, for example, with a conveyer belt 12 feet wide,it is advisable that the vapor booth top carry two sets of blowers orfans, for circulation of the coating material vapor. In vapor boothsthat are 12 feet wide, the two sets of blowers, or fans, are equallyspaced from the booth sides, preferably about three feet to four feetfrom each side, and the blowers, or fans in each plenum preferablyrotate in the same direction.

FIG. 3 illustrates the means forming the vapor booth from above andwithout a blanket of insulation 50 to show other features of the vaporbooth. For example, the upper plate may be provided with a plurality ofdoors 51 permitting access into the plurality of plenums from above thevapor coating booth.

Because the coating apparatus 10 is located generally adjacent theannealing lehr for the glassware, the glassware is carried through thevapor coating means 40 while still at an elevated temperature and heattransfer from the heated glassware will maintain the enclosed containerportion at an elevated temperature. Accordingly, the inclusion of stripheaters on the booth top may be needed only to supplement the heattransferred into the enclosed conveyer portion by the glassware, or toplace the vapor booth is in the ready condition when glassware is notbeing coated.

As clear from the description above, applicant's invention provides amethod for forming a coating on glassware by conveying a series aglassware articles to be coated at elevated temperatures through acoating zone adjacent a portion of the conveyer. By providing means 40,a portion of the conveyer is enclosed and thermally isolated to providea coating zone, and the coating zone may be heated to provide anelevated temperature along the conveyer portion. By liquefying normallysolid coating material through the elevation of its temperature, aplurality of controlled flows of liquified coating material may beproduced and directed at elevated temperatures to a plurality of coatingmaterial atomizers, or vaporizers. By additionally producing anddirecting a plurality of control flows of heated pressurized air to theplurality of vaporizers, a plurality of controlled flows of liquifiedcoating material may be atomized or vaporized with the plurality ofcontrolled flows of heated pressurized air, and the atomized liquifiedcoating material may be entrained in a plurality of flows of heated air.The plurality of flows of heated air and entrained particles ofliquified coating material may be directed from the atomizers into aheated vapor chamber, which can remove by gravity of non-vaporous, i.e.,high mass to surface ratio, coating material particles, and a pluralityof flows of heated air and entrained vaporous liquified coating materialare directed to the enclosed and thermally isolated coating zone. Byproviding a plurality of circulating and counter-rotating currents ofheated air in the enclosed and thermally isolated coating zone, and byintroducing the plurality of flows of heated air and entrained vaporouscoating material into the plurality of circulating, counter-rotatingcurrents of heated air within the enclosed and thermally isolatedcoating zone, a series of glassware articles may be coated byimpingement of the coating material particles on the glassware articlesin the coating zone, and upon removal of the glassware articles from theheated, thermally isolated coating zone, the deposited coating materialcools to form a solid coating on the glassware.

A preferred coating material for use with this method is stearic acid(octadecenoic acid), which has a melting point of about 70° C. or 157°F. Stearic acid oxidizes easily at elevated temperatures and degrades atthe elevated temperatures of glass manufacturing operations; thus, theapplication of stearic acid must be carefully effected. In the apparatusand method of the invention, however, stearic acid is liquified,atomized and deposited and forms a tenacious bond to hot end metal oxidecoated surfaces of glassware, it is believed, through the --COOH groupof the stearic acid. With the method and apparatus of this invention,one to two pounds of stearic acid, uniformly applied, can provide theeffective coating of this invention on one gross of glass containers,such as baby food jars, per minute for three shifts, or about 24 hours,can eliminate the need for an additional polyethylene cold end coatingand may reduce the hot end tin oxide coating by one-half.

EXAMPLE I

A prior art coating apparatus like that described and shown in FIG. 9 ofU.S. Pat. No. 3,989,004 was used to provide a commercial prior artcoating for comparison with the invention. Oleic acid was atomized in anatomizer thereby forming oleic acid vapor and conducted into the coatinghood. Circulation of the vapor was accomplished by a fan operating inthe manner shown in FIG. 9 of U.S. Pat. No. 3,989,004.

A first portion of glassware which had received a tin oxide hot endcoating was placed in the coating hood at a temperature somewhat above200° F. for a period of about 120 seconds. The vapor was maintainedabove the vaporization point of the oleic acid. The treatment resultedin formations of a completely transparent coating on the glasswaresamples.

The invention was then used to prepare samples for comparative testing.A coating apparatus as shown and described above was used to coat asecond portion of the glassware that had received the tin oxide hot endcoating. The vapor booth 40 was heated to a temperature of 250° F. Solidstate stearic acid was liquified in the reservoir 22 and provided tomeans 28 for providing micron-sized coating material particles in a flowof heated air. The resulting micron-sized particles, or vapor, of liquidstearic acid were introduced into the vapor booth 40 at a rate of onepound of solid material per day. The second portion of the glassware wasplaced in the vapor booth 40 at about 250° F. and the bottles wereexposed to coating material in the vapor booth 40 for a period of 120seconds.

Samples were selected at random from the first portion of glassware,which was provided by the prior art with an oleic acid coating, and fromthe second portion of glassware which was coated with the invention. Thesamples with both coatings were placed in an autoclave, which wasprovided with steam at 250° F. and 15 pounds per square inch for onehour. The samples were then removed from the autoclave and allowed tocool for testing.

The samples were then tested for scratch resistance using an industrystandard scratch test. Only 25 pounds of force resulted in scratches inthe autoclaved samples that had been provided by the prior art with anoleic acid coating. The scratch resistance of the autoclaved samplescoated with the invention exceeded the test force available with thetest equipment, that is, with the test equipment applying its maximumforce, the stearic acid coated samples remained scratch resistant atforces exceeding 70 pounds.

EXAMPLE II

A third portion of glassware, which had received a tin oxide coatinghaving one-half the weight of the first and second portions of ExampleI, was coated with the invention in the same manner as the secondportion of Example I, was placed in the autoclave with the first andsecond portions of Example I, and was removed from the autoclave andtested for scratch resistance in the same manner as the first and secondportions of Example I. The third portion of glassware, which had beenprovided with a stearic acid coating in accordance with the invention,over a tin oxide hot end coating of one-half the weight of the hot endcoatings of the first and second portions, also had a scratch resistancethat exceeded the test force available with the test equipment.

With this invention, glassware can be provided with an unexpectedlyeffective coating by providing the glassware to be coated to an enclosedconveyer portion, atomizing normally solid coating material into liquidmicron-sized, vaporous particles, circulating the resulting liquidparticles in a heated thermally isolated coating zone adjacent theglassware surfaces to be coated, and depositing the micron-sized liquidcoating material particles on the hot glassware surfaces with flows ofheated air. The method is performed at a temperature greater than themelting point of the coating material but below its degradationtemperature, for example, preferably in the range from about 250° F. toabout 300° F. and most preferably at about 250° F. where stearic acid isused. The glassware is preferably at a temperature of about 250° F. butmay be at a lesser temperature, preferably above the melting point ofthe coating material. In the method, a continuous coating need not beformed. Notwithstanding the lack of coating continuity, the resultantcoating can be unexpectedly lubricous and durable and provide the otheradvantages set forth above.

Various modifications may be made in the method and apparatus shown anddescribed above without departing from the scope of this invention asdefined by the prior art and the claims that follow.

We claim:
 1. Apparatus for applying a coating to glassware, comprising:asource of pressurized air; means forming a source of liquid coatingmaterial, comprising a reservoir having a top, a bottom and at least onesidewall therebetween, and a first electric heater for said reservoir,an inlet for a pressurizing gas formed in said reservoir, said inletbeing connected with an adjustable gas pressure regulator, a coatingmaterial outlet tube carried by said reservoir with a withdrawal openingadjacent the reservoir bottom, a level sensor carried by the reservoirto signal the level of liquid coating material in said reservoir, and atemperature sensor providing a signal for control of said electricheater to maintain the liquid state of coating material in saidreservoir; said adjustable gas pressure regulator providing a regulatedgas pressure in said reservoir and a regulated flow of liquid coatingmaterial from said outlet tube; means for forming a coating materialvapor, comprising a vapor chamber including a top, a bottom and at leastone sidewall therebetween, a second electric heater for said vaporchamber, a plurality of vapor-forming atomizers carried by said chambertop, each of said plurality of vapor-forming atomizers having a coatingmaterial inlet connected with said outlet tube for receipt therefrom ofsaid regulated flow of coating material and also having an atomizing airinput, each of said vapor-forming atomizers having coating material andatomizing air outlets coacting to form and direct coating material vaporinto said vapor chamber, an enclosure for said source of liquid coatingmaterial and said vapor-forming means; means forming a vapor booth for aportion of a conveyer operable to carry articles of glassware throughthe vapor booth, said means forming a vapor booth comprising a boothtop, an upper plate and a plurality of partitions therebetween forming aplurality of plenum chambers, arranged one after the other, over andalong the conveyer portion, a pair of downwardly extending side-formingmeans for said vapor booth, said booth side-forming means providingmeans for supporting said vapor booth with respect to said conveyerportion, each of said pair of booth side-forming means being open and incommunication with each of the plurality of plenums and carrying aplurality of flow directing and controlling vanes, said upper plate ofsaid means forming a vapor booth having a plurality of openings, one ineach of the plurality of plenums, for carrying a fan in each of theplurality of plenums, said booth top having a plurality of openings, atleast one for each plenum, permitting vapor flow between the pluralityof plenums and the conveyer enclosure formed by the booth top and sides,said booth top carrying at least one heater, and a plurality offlow-producing fans and fan motors carried by said upper plate with onefan being located in each plenum; and a plurality of vapor dischargetubes in communication with said reservoir of said vapor-forming meansand extending into the vapor booth and arranged at a plurality oflocations along the conveyer portion, said fans being rotated by theirfan motors to provide circulating flows of coating material vapor withinthe booth and along the conveyer portion, said apparatus furthercomprising a vapor confining plate below the conveyer portion and underthe vapor booth.
 2. The apparatus of claim 1 wherein said plurality ofopenings in said booth top include a plurality of fan openings locatedwith respect to said plurality of plenums and the conveyer enclosure,and said plurality of fans have their blades operatively associated withsaid plurality of fan openings to provide vapor circulation within theconveyer enclosure and plenums.
 3. The apparatus of claim 2 wherein thefan blades are partially ducted.
 4. The apparatus of claim 2 wherein thefan blades are alternating opposite directions to providecounter-rotating flows of coating material vapor within the conveyerenclosure.
 5. The apparatus of claim 1 further comprising further meansupstream of said vapor booth for applying an metal oxide coating to theglassware.
 6. The apparatus of claim 1, where each of said atomizing airinlets of said plurality of vapor-forming atomizers is connected with anair heater that is connected through an air flow regulator with saidsource of compressed air.
 7. Apparatus for applying a coating toglassware, comprising:means for providing a regulated flow of heated andliquified coating material; vapor-forming means for forming saidregulated flow of heated and liquified coating material into a coatingmaterial vapor with a heated and regulated flow of gas; means forproviding said vapor-forming means with a heated and regulated flow ofpressurized air; means forming a vapor booth for a portion of a conveyeroperable to carry articles of glassware through the vapor booth, saidmeans forming a vapor booth comprising a booth top, an upper plate and aplurality of partitions therebetween forming a plurality of plenumchambers, arranged one after the other, over and along the conveyerportion, a pair of downwardly extending side-forming means for saidvapor booth, said booth side-forming means providing means forsupporting said vapor booth with respect to said conveyer portion, eachof said pair of booth side-forming means being open and in communicationwith each of the plurality of plenums and carrying a plurality of flowdirecting and controlling vanes, said top plate of said means forming avapor booth having a plurality of openings, one in each of the pluralityof plenums, for carrying a fan in each of the plurality of plenums, saidbooth top having a plurality of openings, at least one for each plenum,permitting vapor flow between the plurality of plenums and the conveyerenclosure formed by the booth top and sides, said booth top carrying atleast one heater, and a plurality of flow-producing fans and fan motorscarried by said top plate with one fan being located in each plenum,said vapor booth being encased in thermal insulation; and a plurality ofvapor discharge tubes in communication with said vapor-forming means andextending into the booth and arranged at a plurality of locations alongthe conveyer portion, said fans being rotated by their fan motors inalternating opposite directions to provide a plurality ofcounter-rotating flows of coating material vapor within the booth andalong the conveyer portion, said apparatus further comprising a vaporconfining plate below the conveyer portion and under the vapor booth. 8.Apparatus for applying a coating of high temperature melting pointcoating material to hot glassware comprising:a source of pressurizedair; a temperature-controlled reservoir of liquified coating material,said reservoir having a top, a bottom and at least one sidewalltherebetween, a first electric heater for liquefying coating material insaid reservoir, an inlet for a pressurizing gas formed in saidreservoir, said inlet being connected with an adjustable gas pressureregulator, a coating material outlet tube carried by said reservoir witha withdrawal opening adjacent the reservoir bottom, a level sensorcarried by the reservoir to sense the level of liquid coating materialin said reservoir, and a temperature sensor for providing a signal forcontrol of said electric heater to maintain the liquid state of coatingmaterial in said reservoir; said adjustable gas pressure regulatorproviding a regulated gas pressure in said reservoir and a regulatedflow of liquid coating material from said outlet tube; a heated coatingmaterial vapor-forming means, comprising a vapor chamber including atop, a bottom and at least one sidewall therebetween, a second electricheater for said vapor chamber, a plurality of vapor-forming atomizerscarried by said chamber top, each of said plurality of vapor-formingatomizers having a coating material inlet connected with said reservoiroutlet tube for receipt therefrom of said regulated flow of liquidcoating material and also having an atomizing air input, each of saidvapor-forming atomizers having coating material and atomizing airoutlets coacting to form and direct coating material vapor into saidvapor chamber, and a thermally isolated and partially heated vapor boothconnected with said vapor-forming means and enclosing a portion of aconveyer for carrying said hot glassware through said vapor booth, saidthermally isolated and partially heated vapor booth comprising meansforming at least one plenum in the vapor booth, said plenum having anopening in communication with the enclosed conveyer portions and fanmeans for creating a circulation of coating material vapor within saidplenum and said enclosed conveyer portion.
 9. The apparatus of claim 8further comprising thermocouple means for preventing operation of saidvapor-forming means at less than a preset temperature and formaintaining said reservoir at a preset temperature.
 10. The apparatus ofclaim 8 wherein said thermally isolated and partially heated vapor boothcomprises a booth top, a top plate and a plurality of partitionstherebetween forming a plurality of plenum chambers arranged, one afterthe other, over and along the conveyer portion, a pair of downwardlyextending side-forming means for said vapor booth, said boothside-forming means providing means for supporting said vapor booth withrespect to said conveyer portion, each of said pair of boothside-forming means being open and in communication with each of theplurality of plenums and carrying a plurality of flow directing andcontrolling vanes, said top plate having a plurality of openings, atleast one in each of the plurality of plenums, for carrying a fan ineach of the plurality of plenums, said booth top having a plurality ofopenings, at least one for each plenum, permitting vapor flow betweenthe plurality of plenums and the conveyer enclosure formed by the boothtop and sides, said booth top carrying at least one heater, andaplurality of flow-producing fans and fan motors carried by said topplate with one fan being located in each plenum.
 11. The apparatus ofclaim 10 wherein:said fans are rotated by their fan motors inalternating opposite directions to provide a plurality ofcounter-rotating flows of coating material vapor within the conveyerenclosure along the conveyer portion.
 12. The apparatus of claim 8comprising:a plurality of vapor discharge tubes in communication withthe vapor-forming means and extending into the booth and arranged at aplurality of locations along the conveyer portion, at least one vapordischarge tube being located to direct a flow of coating material vaporinto the flow of each plenum.
 13. The apparatus of claim 8 furthercomprising a thermally insulating enclosure for said vapor booth. 14.The apparatus of claim 10 wherein said plurality of opening in saidbooth top include a plurality of partially ducted fan openings centrallylocated with respect to said plurality of plenums and the conveyerenclosure, and said plurality of fans have their blades operativelyassociated with said plurality of fan openings to provide vaporcirculation within the conveyer enclosure and plenums.
 15. The apparatusof claim 8, where each of said atomizing air inlets of said plurality ofvapor-forming atomizers is connected with an air heater that isconnected, through an air flow regulator, with said source of compressedair.
 16. Apparatus for supplying a coating to glassware, comprising:asource of pressurized air; an adjustable gas pressure regulator coupledto the source of pressurized air; a tank having a reservoir and vaporchamber separated by an internal wall for containing liquid andvaporized coating material, the tank having inlet means coupled to theadjustable gas pressure regulator, a coating material outlet tubecarried by said tank means with a withdrawal opening adjacent the bottomof said tank, a level sensor carried by the tank to signal the level ofliquid coating material in said tank, and a temperature sensor providinga signal for control of an electric heater to maintain the liquid stateof coating material in said tank, said adjustable gas pressure regulatorproviding a regulated gas pressure in said tank and a regulated flow ofliquid coating material from said outlet tube; means for forming acoating material vapor comprising an electric heater for said tank andat least one vapor-forming atomizer, the at least one vapor-formingatomizer having a coating material inlet connected to said tank and anair inlet coupled to the adjustable gas pressure regulator and a coatingmaterial outlet and an atomizing air outlet coacting to form and directcoating material vapor into said tank; and means for forming a vaporbooth for a portion of a conveyer operable to carry articles ofglassware through the vapor booth.
 17. The apparatus of claim 16,wherein the internal wall includes valve means positioned therein forfluidly connecting the reservoir and vapor chamber so thatpressurization of the vapor chamber forces condensed coating materialvapor through the valve means into the reservoir.
 18. Apparatus forapplying a coating to glass, comprising:vapor-forming means for forminga regulated flow of heated and liquified coating material into a coatingmaterial vapor with a regulated flow of gas; means forming a vapor boothfor a portion of a conveyor operable to carry an article of glassthrough the vapor booth; tank means forming a coating material reservoirand vapor chamber separated by a common wall for containing liquid andvaporized coating material, the tank means having a pressure inletmeans, a coating material outlet tube carried by said tank means with awithdrawal opening adjacent the bottom of said coating materialreservoir, a level sensor carried by the tank means to signal the levelof liquid coating material in said coating material reservoir, and atemperature sensor providing a signal for control of an electric heaterto maintain the liquid state of coating material in said tank means,said vapor-forming means being carried by and in a heat transferrelationship with said tank means, with a coating material inletconnected with said coating material outlet tube, said vapor-formingmeans directing vapor formed from said coating material into said vaporchamber, and means for providing said vapor-forming means with aregulated flow of pressurized gas and for also providing a regulated gaspressure in said tank means and a regulated flow of liquid coatingmaterial from said outlet tube.
 19. The apparatus of claim 18, whereinthe vapor-forming means includes at least one vapor-forming atomizermounted against the tank means having a coating material inlet connectedto said coating material outlet tube at its interface with said tankmeans and an air inlet coupled to the adjustable gas pressure regulator,and a coating material outlet and an atomizing air outlet coacting toform and direct coating material vapor into said vapor chamber at itsinterface with said tank means.
 20. The apparatus of claim 19, whereinthe tank means includes a tank having a reservior and vapor chamberseparated by an internal wall, the internal wall having valve meanspositioned therein for fluidly connecting the reservoir and vaporchamber.
 21. Apparatus for applying a high temperature melting pointmaterial to hot glass, comprisinga conveyer for the hot glass; acontrollable source of compressed gas; a unitary source of liquifiedcoating material particles connected with the controllable source ofcompressed gas, comprising a tank having a top, a bottom and at leastone sidewall forming a reservoir for liquified coating material and anadjacent particle chamber separated by an internal wall, a coatingmaterial tube in said reservoir with a withdrawal opening adjacent thereservoir bottom and a coating material outlet, at least one atomizercarried by the tank spanning the internal wall with an inlet connectedto the outlet of the coating material tube and a spray outlet directedthrough a tank opening into the particle chamber, and at least oneheater for maintaining the coating material in a liquified state withinthe tank and atomizer, said controllable source of compressed gasproviding a flow of liquified coating material from the reservoir to theatomizer and operation of said atomizer to provide a flow of coatingmaterial particles into the particle chamber and to carry gas-bornecoating material particles from a particle outlet adjacent the tank top;and a heated vapor booth adjacent to and partially enclosing saidconveyer for hot glass and forming a coating chamber for the hot glass,said vapor booth being connected with the particle outlet of saidunitary source of liquified coating material particles so said coatingmaterial particles are deposited on the hot glass carried by theconveyer through the vapor booth.
 22. The apparatus of claim 21 whereinsaid particle chamber includes a recovery chamber adjacent its bottomfor recovery of coating material particles too large to be carried fromthe particle outlet, and said common internal wall includes an openingwith a check value between the particle chamber and reservoir wherein apressure differential between said particle chamber and reservoir canreplenish said reservoir with recovered coating material.
 23. Theapparatus of claim 21 wherein said at least one heater is in heattransfer relationship with at least one sidewall of the tank, said tanktop and at least one sidewall being in heat transfer relationship, saidat least one atomizer being carried by and in heat transfer relationshipwith the tank top.
 24. In an apparatus for applying a high temperaturemelting point material to a substrate, the improvement comprising aunitary heated tank connectable with a controllable source of compressedgas, said tank having a top, a bottom and at least one sidewall andforming a reservoir for liquified coating material and an adjacentparticle chamber separated by an internal wall, a coating material tubein said reservoir with a withdrawal opening adjacent the reservoirbottom and a coating material outlet, at least one atomizer carried bythe tank with an inlet connected to the outlet of the coating materialtube and a spray outlet directed through a tank opening into theparticle chamber, and at least one heater in heat transfer relationshipwith said reservoir, particle chamber and atomizer for maintaining thecoating material in a liquified state within the tank and atomizer, saidcontrollable source of compressed gas being connectable with said tankto generate a flow of liquified coating material from the reservoir tothe atomizer, and to operate said atomizer to provide a flow of coatingmaterial particles into the particle chamber and a flow of coatingmaterial particles from a particle outlet adjacent the tank top.